Detection of submicroscopic lymph node metastases in patients with melanoma.

A cell culture technique was developed to investigate submicroscopic lymph node metastases in patients with stage 1 or 2 malignant melanoma. Lymph nodes were isolated from standard dissections and bivalved. Half of the node was evaluated by routine histopathologic examination, while the other half was processed and placed into tissue culture. Three hundred twenty-three lymph nodes were collected from 41 patients. The cell culture technique identified 155 of 323 lymph nodes containing micrometastases, while only 20 of 323 lymph nodes tested positive with routine histochemical processing. Nine patients were upgraded from stage 1 or 2 to stage 3 disease after micrometastases were identified in lymph node cultures. Identification of melanoma was confirmed by cytologic examination, immunohistologic staining, and the presence of GD3 ganglioside and 250-kd glycoprotein melanoma-associated antigens. This study provides evidence that the culture of lymph nodes is a sensitive method for the detection of micrometastases. In addition, this procedure may change prognosis and identify candidates for adjuvant therapies.